Method for creating a fabric with a colored pattern

ABSTRACT

A fabric formed from cellulosic fibers is printed with a dye gain print paste including an acrylic copolymer and/or a dye resist print paste including an acrylic copolymer. The fabric may then be cut into garment pieces, which are made up into garment modules, and the garment modules are dyed.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims benefit of Provisional Application No.60/236,631 filed Sep. 29, 2000. The entire disclosure of ProvisionalApplication No. 60/236,631 is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] This invention relates to a method for creating a fabric with acolored pattern.

[0003] Whether a pattern is perceptible by the human eye depends on thegranularity or detail of the pattern. A pattern that is sufficientlycoarse to appear as discrete black and white checks or stripes at adistance of one meter would typically appear a uniform gray at adistance of 100 meters. Conversely, a fabric that appears to be uniformgray at a distance of one meter may be seen to be composed of black andwhite yarns when viewed through a microscope. Thus, the term “pattern”does not imply distribution of color in discrete areas with distinctedges when viewed at a distance of one meter or so but covers a colordistribution that may appear uniform at a distance of one meter but whenviewed more closely can be seen to be a blend of discrete areas withdistinct edges.

[0004] A fabric garment can be made by forming a fabric from textileyarns, cutting the fabric into garment pieces, and sewing the garmentpieces together. The fabric can be made by knitting or weaving the yarnsto form knits or woven fabrics or by bonding the yarns to form non-wovenfabrics. Color can be imparted to the yarns at four stages: in fiberdyeing, the fibers are dyed in advance of spinning into yarns, and thedyed fibers are spun into yarns; in package dyeing, the yarns are dyedbefore they are knit or woven to form the fabric; in fabric dyeing, thefabric is dyed after it has been knit or woven but before it is cut intogarment pieces; and in garment dyeing, the manufactured garment is dyed.

[0005] The conventional garment dyeing process for cellulose fiber(cotton) garments using a reactive (direct) or acid dye involves placingcompleted garments in a paddle dye (or rotary) machine containing water,adding certain chemicals, including an electrolyte such as sodiumsulfate or sodium chloride, to the process bath and allowing thegarments to circulate, adding the dye to the bath, and heating the bathat about 3° F. per minute to the exhaust temperature, which depends onthe particular dye and is typically 140 to 160° F. When the exhausttemperature is reached, an alkali is added to the bath to begin theexhaustion and fixation of the dye to the cellulose fiber. The bath isheld at the exhaust temperature for an extended period of time, which issufficient for fixation of the dye and may typically be about 45minutes, and the machine is then drained.

[0006] Hitherto, garment dyeing has been unsatisfactory and has not beencommercially acceptable for many purposes because dye penetration intothe fabric has been poor and non-uniform, particularly at the seams, andexcessive abrasion to the fibers has occurred.

[0007] Conventionally, a fabric having a colored pattern is createdeither by weaving or knitting threads of different colors so that thepattern is created as the fabric is created, or by applying coloringmedium, such as dye, to the completed fabric in accordance with aspatial pattern. In the latter case, the pattern may be imparted by aprinting process using stencil-like screens to define the areas to whichcoloring medium is applied.

[0008] Hand block printing and hand screen printing techniques requirerelatively modest capital costs but these techniques are not suitablefor long print runs and consistency of print is not guaranteed in repeatapplications. Moreover, operating costs are high.

[0009] Rotary printing machines not only run at high speed but alsoensure consistency of prints and better clarity and registrationcompared to block and screen printing. Further, modern rotary machinescan give various designs repeats also.

[0010] In the past some attempts have been made to apply dye resist anddye gain agents to cellulosic fabrics and garments by screen printing,either by hand or by machine, but efforts to apply such agents using ahigh speed rotary printing machine have not been successful.

[0011] The commonly available dye resist and dye gain chemicals are notvery durable when washed and can be easily felt by hand.

[0012] U.S. Pat. No. 5,984,977 discloses a further technique forimparting a colored pattern to fabric. In accordance with thistechnique, a dye blocking or dye enhancing paste is applied to thefabric by printing, so that some areas of the fabric receive the pasteand other areas do not. The fabric is then dyed, and the effectivenessof the dye on the fabric is different on the areas that were printedwith the paste than on the areas that were not printed.

[0013] In accordance with the disclosure in U.S. Pat. No. 5,984,977, thedye blocking paste includes a pre-catalyzed cross-linking glyoxal resinand a low molecular weight polyacrylic acid and the dye enhancing pasteincludes an epoxy functional quaternary ammonium compound. Althoughthese pastes are suitable for application to fabric by screen printing,it has been found that they are not suitable for application using arotary printing machine.

SUMMARY OF THE INVENTION

[0014] In accordance with the invention there is provided a method ofcreating a fabric with a colored pattern, comprising (a) providing atleast first and second yarns, wherein the first yarn has a greateraffinity than the second yarn for a selected dye, (b) creating a fabricusing at least the first and second yarns, and (c) dyeing the fabricusing the selected dye.

[0015] The present invention provides several techniques for achievingdifferential dye pick up during dyeing of fabric, particularly garmentdyeing, by printing with a polymer-based dye gain agent and/or apolymer-based dye resist agent. These techniques allow the dye pick upto be increased and/or reduced in selected areas of the fabric relativeto other areas. Consequently, when the fabric is dyed, the depth orsaturation of the shade is greater in areas that have been treated withthe dye gain agent and is less in the areas that have been treated withthe dye resist agent, in each case relative to untreated areas. Theextent of the difference in depth can be adjusted by controlling theconcentration of the dye gain agent or dye resist agent in the printingpaste.

[0016] In accordance with one aspect, the present invention is appliedto fabric that has previously been formed and in accordance with anotheraspect, the present invention is applied to formation of fabrics fromyarns that have been differently treated to achieve differential dyepick up.

[0017] Certain acrylic copolymers are particularly advantageous as dyeresist and dye gain agents in methods embodying the present invention.For example, a highly anionic copolymer composed of acrylic polymer,pigment (such as titanium dioxide) and softeners is effective as a dyeresist agent with respect to anionic dyes, such as reactive, modifiedreactive and direct dyes, and a highly cationic copolymer composed ofacrylic polymer, styrene monomer, acrylate and softeners is effective asa dye gain agent with respect to the same anionic dyes. The acryliccopolymer is synthesized from acrylic monomers, and the cationic (oranionic) nature of the acrylic copolymer is controlled by selectingappropriate monomers from which to synthesize the copolymer. Thus, somemonomers will result in the acrylic copolymer being anionic in natureand other monomers will result in the acrylic copolymer being cationicin nature.

DETAILED DESCRIPTION EXAMPLE I

[0018] A first method in accordance with the invention is used tointensify the effect of dye on a fabric. This first method includes fivemain operations:

[0019] A. Prepare greige fabric for dyeing by the following process:

[0020] 1. If the fabric was sized during weaving, the fabric is desizedusing enzymes. If the fabric was not sized during weaving, omit step 1.

[0021] 2. The fabric is placed in a water bath at 380 C and scouring andbleaching agents are added to the water bath. The bath containing thefabric and the scouring and bleaching agents is heated to 95° C. at 2°C. per minute and is held at 95° C. for 45 minutes. The fabric is cooledin steps by several rinses to avoid cracking, which may result in dyestreaks during the subsequent garment dyeing process. The pH of the bathis adjusted to the range 6-7 and a peroxide killer is added to theneutralized bath to remove any hydrogen peroxide residues.

[0022] The bleaching and scouring agents are:

[0023] 5-6% hydrogen peroxide (50%)

[0024] 4-5% caustic soda (50%)

[0025] 2-3% peroxide stabilizer (non silicate)

[0026] 1% cleaning agent (Sandoclean PCJ)

[0027] 1-2% lubricating and wetting agent (Imacol CI)

[0028] 0.25-0.5% chelate (sequestrant)

[0029] where percentages are by volume of the water bath. Softenersshould be avoided, but if softeners are included they should benon-ionic softeners. The bleaching and scouring operation removes waxes,pectins and foreign matter from the fabric and opens up the dye sites inorder to maximize color pick up.

[0030] B. Prepare a dye gain print paste by the following process:

[0031] 1. Thoroughly mix 15 parts water and 5 parts kerosene emulsifierand then slowly add 80 parts of mineral turpentine oil (MTO) orkerosene. Stir the mixture until a stable emulsified paste is formed.

[0032] 2. Prepare a dye gain paste by thoroughly mixing 50 parts ofcationic dye gain material and 50 parts of water. A suitable dye gainmaterial is formulated by addition of acrylic copolymer, styrenemonomers and acrylates.

[0033] 3. Prepare the print paste by slowly adding 76 parts of dye gainpaste to 24 parts of MTO/kerosene paste under constant stirring, andcontinuing stirring until a uniform homogeneous paste is formed.

[0034] C. Apply the dye gain print paste to the prepared for dyeing(PFD) fabric in accordance with a spatial pattern using a flatbedprinting machine, as is conventional for screen printing fabric, orusing a rotary printing machine, which is advantageous because it allowsprinting at a higher speed. The viscosity of the dye gain print pastecan be reduced if necessary by addition of water.

[0035] The printed fabric is first dried at 80-90° C. and then heated to130-135° C. for five minutes in order to cure the polymer of the dyegain material and bond it to the fabric.

[0036] D. Cut the fabric into garment pieces and make the garment piecesup into garment modules. Since the dye gain print paste is colorless,acrylic dye may be added to the print paste to impart a tint to thepaste for ease of cutting.

[0037] E. Overdye the garment modules using anionic dyes. The cationicsites of the dye gain material attract the dye anions and consequentlystrong dye yields are observed at the areas to which the dye gain printpaste has been applied. The areas to which the dye gain print paste hasbeen applied pick up the dye with a deeper or more intense shade thanother areas, thus providing a two-tone effect having areas of deepercolor and areas of normal color.

[0038] The difference in shade between the areas that have received thedye gain print paste and the areas that have not received the dye gainprint paste depends on the proportion of dye gain paste in the printpaste. A lighter dye gain is achieved by mixing the dye gain paste andMTO/Kerosene paste in proportions 65:35 or 50:50 instead of 76:24.

[0039] The method described above allows much of the work in manufactureof a garment for sale to be carried out before the retailer specifiesthe color of the garment. The garment modules can be made in onelocation, far from the retailer, and delivered to an overdyeing facilitycloser to the retailer. Garment modules that have been prepared in themanner described above are resistant to normal atmospheric conditionsfor months. Consequently, they can remain in storage at the overdyeingfacility for an extended period without deterioration. When a retailerplaces an order for a particular color, the required garment modules areoverdyed, finished and packed for delivery. These final steps can becompleted in a few days, allowing rapid response to changes in marketdemands.

EXAMPLE II

[0040] A second method in accordance with the invention is used tomoderate the effect of overdye when applied to fabric. This secondmethod involves five main operations:

[0041] A. Greige fabric is prepared for dyeing using the same process asin Example I.

[0042] B. A dye resist print paste is prepared by thoroughly mixing 99parts dye resist polymer (by weight), one part (by weight) of catalyst,and pigment of a nature and in a proportion depending on the color andintensity desired. The dye resist polymer is an acrylic copolymer. Inthe event that it is desired that the dye resist paste be white, thepigment may be titanium dioxide; and in the event another color isdesired, another suitable pigment is used. The paste is mixed thoroughlyunder continuous stirring.

[0043] C. Apply the dye resist print paste to the PFD fabric inaccordance with a spatial pattern using a flatbed printing machine or arotary printing machine, as described in Example I. The viscosity of thedye resist print paste can be reduced if necessary by addition of water.

[0044] The printed fabric is dried and cured as in the case of ExampleI. The catalyst promotes the reaction whereby the acrylic copolymer inthe dye resist paste cross links with the fabric.

[0045] D. Cut the fabric into garment pieces and make the garment piecesup into garment modules, as described in connection with Example I.

[0046] E. Overdye the garment modules using anionic dyes. Preferably,the dyes are reactive or direct, as in the case of Example I. The dyeresist print paste is highly anionic and therefore the areas of agarment module to which the print paste has not been applied pick up theoverdye color while the areas to which the print paste has been applieddo not but on the contrary retain the color imparted by the pigmentincluded in the dye resist print paste. Consequently, the color of thegarment module is not restricted to greater and lesser depths of theoverdye color, and if the garment module is made up of pieces that havebeen printed using dye resist print pastes with different pigments, thevarious pieces of the garment module have the colors respectivelyassociated with the pigments but are unified by the color of theoverdye.

[0047] The method described in Example II has similar advantages toExample I with respect to choices of color and rapid repsonse to marketdemands.

EXAMPLE III

[0048] A third method in accordance with the invention is used to bothintensify and moderate the effect of overdye on a cellulosic fabric indifferent respective areas.

[0049] This third method involves ** main operations:

[0050] A. Prepare greige fabric for dyeing by the process described inExample I.

[0051] B1. Prepare a dye gain paste in accordance with step B of ExampleI.

[0052] B2. Prepare a white or colored dye resist print paste inaccordance with step B of Example II.

[0053] C. Apply the dye gain print paste to selected areas of the PFDfabric and apply the dye resist print paste to other areas of the PFDfabric at respective stations of a suitable printing machine, such as arotary printing machine. The viscosity of the one or both print pastescan be reduced if necessary by addition of water. Dry the printed fabricand cure the polymer as described in Examples I and II.

[0054] D. Cut the fabric into garment pieces and make up the garmentpieces into garment modules as described in Examples I and II.

[0055] E. Overdye the garments modules by the exhaust method usingdirect or reactive dyes.

[0056] The dye resist and dye gain agents are acrylic copolymers thatare used in accordance with the present invention are synthesized withhigh value softeners to avoid peel off. Further, these new polymers areformulated on different monomer basis and cannot be felt by hand afterprinting and do not peel off after repeated washings.

EXAMPLE IV

[0057] A first batch of cotton yarn is treated on a package dye machinewith a cationic polymer that renders the cotton yarn receptive to aciddyes. A suitable cationic polymer is polyamide epichlorhydrin. A secondbatch of cotton yarn is dyed in conventional manner by package dyeingand dried. Different packages in the second batch may be dyed withdifferent colors. The dyed yarns of the second batch and the treatedyarns of the first batch are knit or woven together to form a fabric andthe fabric is scoured and finished in conventional fashion, withoutbleaching. The scouring process removes foreign matter, such as waxesand pectins, and thereby opens up the dye sites of the fabric andmaximizes color pick-up. The fabric is then cut into garment pieceswhich are sewn to form a garment. At this point the garment is not readyfor retail sale because the treated yarns have not been dyed. Thegarment is dyed using an acid dye that has an affinity for the cottonyarn that has been treated with the cationic polymer and will fix to theyarns of that cotton. However, because the acid dye has no affinity forthe untreated cotton yarns the dye molecules will not fix to the cottonthat has previously been dyed. Consequently, depending on the nature ofthe pattern in which the treated yarns and dyed yarns are knit or woven,the cotton garment has a colored pattern or the perceived color of thegarment is a blend of the color of the dyed yarns and the color that isimparted to the treated yarns by the acid dye.

[0058] EXAMPLE V

[0059] Mercerizing is a form of chemical treatment that involvestreatment with caustic soda. Mercerized cotton yarns have a greateraffinity for certain dyes than nonmercerized cotton yarns.Conventionally, a fabric has been made either from all mercerized yarnsor from all nonmercerized yarns.

[0060] In accordance with the invention, mercerized yarns andnonmercerized yarns are knit or woven together in the same fabric, whichis then scoured. The fabric is compacted (in the case of knit fabric) orsanforized (in the case of woven fabric) to control shrinkage. Garmentpieces are cut from the fabric and sewn together to form a garmentmodule and the garment module is dyed using a dye that has differentialaffinity for mercerized and nonmercerized yarns, such as a reactive,direct or pigment dye. The different affinity for dye of mercerizedyarns and nonmercerized yarns results in a visual difference between themercerized and nonmercerized yarns. The visual difference is moreprominent with light or medium dyes than with dark dyes, which mayprovide a tonal effect rather than a visually discernible colordifference.

EXAMPLE VI

[0061] A first batch of cotton yarn is dyed and the dyed yarn ischemically treated with a dye resist agent and is processed in order tocure the agent. For example, a suitable dye resist agent is a reactivesilicone. In this case, the dyed yarn is dipped in hank form into asolution of reactive silicone (such as the material sold by Britacellunder the designation Microsil) and is placed in an infrared oven sothat the silicone is cured and thereby bonded to the yarn. The siliconeresists absorption of dye into the yarn fiber. Fabric is knit or wovenusing the treated yarns and untreated yarns that have not been dyed. Thefabric is cut into garment pieces that are sewn together to form agarment module. The garment module is dyed. The untreated yarns take thecolor of the dye whereas the silicone prevents the treated yarns fromtaking the color of the dye. The treated yarns retain their originalcolor, which was imparted prior to chemical treatment. Consequently,depending on the weaving or knitting pattern, it is possible to createmulticolored strips or plaids that retain their true colors and do notlook over-dyed.

[0062] The invention is not restricted to the dye resist agent beingreactive silicone and other materials also are suitable. In addition,the invention is not restricted to the material that influences dyeuptake being a material that prevents or reduces dye uptake, and a dyegain agent may be used instead.

EXAMPLE VII

[0063] The affinity of a yarn for a reactive or direct dye depends onthe chemical composition of the yarn. In general, cotton yarns acceptreactive and direct dyes whereas synthetic yarns do not accept reactiveand direct dyes.

[0064] Synthetic yarn that has been fiber-dyed or yarn-dyed and cottonyarn that has not been dyed are woven or knit to create a fabric. Thefabric is cut into garment pieces and the pieces are sewn together toform a garment module, and the garment module is dyed using a reactiveor direct dye. The synthetic yarn is selected so that it does not acceptthe reactive or direct dye whereas the cotton yarn does, and accordinglythe fabric combines the colors of the dyed cotton yarns and thefiber-dyed or yarn-dyed synthetic yarn.

[0065] The synthetic yarn may be a polyester yarn, a nylon yarn or anacrylic yarn, for example. Preferably, the synthetic yarn is spunpolyester, which is made from staple lengths of polyester fiber that arespun into a yarn in similar fashion to that in which cotton yarn ismade, and is similar in hand and appearance to cotton yarn. Theresulting fabric has similar appearance and hand to a 100% cottonfabric.

[0066] Garment dyeing in the manner described above in Examples I-VII isparticularly advantageous because it allows garment modules to be madein advance of the final determination of color. The garment modules canthen be dyed and immediately shipped to retail stores without anyintervening manufacturing steps, as would be necessitated in the case ofa fabric dyeing process. This allows the retailer to respond rapidly tochanges in demand in the marketplace.

EXAMPLE VIII

[0067] In a modification of Examples IV-VII, the fabric includes a yarnwith a different affinity for the dye than the first and second yarns.For example, in the case of Example IV, the third yarn may be apolyester/cotton blend that has a smaller affinity for acid dyes thanthe untreated cotton yarn; or in the case of Example VII, the third yarnmay be a solid base synthetic yarn such as acrylic yarn.

EXAMPLE IX

[0068] In garment dyeing, it has been found that improved performance isobtained if salt is added to the process bath after the dye has beenadded but before starting heating to the fixation temperature. Otherchemicals (particularly alkali) are added to the process bath after thebath has been heated to the exhaustion temperature. It has been foundthat this results in better dye penetration at the seams of the garment,which is desirable in order to produce a quality garment-dyed product.

[0069] It will be appreciated that the invention is not restricted tothe particular embodiments that have been described, and that variationsmay be made therein without departing from the scope of the invention asdefined in the appended claims and equivalents thereof. For example,although the invention has been described in connection with garmentdyeing, which is preferred, certain aspects of the invention may also beapplied to fabric dyeing. Of course, use of fabric dyeing will preventachievement of the advantages that arise from use of garment dyeing.Unless the context indicates otherwise, a reference in a claim to thenumber of instances of an element, be it a reference to one instance ormore than one instance, requires at least the stated number of instancesof the element but is not intended to exclude from the scope of theclaim a structure or method having more instances of that element thanstated.

1. A method of creating a fabric with a colored pattern, comprising: (a)providing at least first and second yarns, wherein the first yarn has agreater affinity than the second yarn for a selected dye, (b) creating afabric using at least the first and second yarns, and (c) dyeing thefabric using the selected dye.
 2. A method according to claim 1,comprising, between steps (b) and (c), making a garment from the fabric.3. A method according to claim 1, wherein step (a) includes treating thefirst yarn with an agent that renders the first yarn receptive to anacid dye and step (c) includes dyeing the fabric with an acid dye.
 4. Amethod according to claim 1, wherein the first yarn is a mercerized yarnand the second yarn is a nonmercerized yarn.
 5. A method according toclaim 1, wherein step (a) includes treating the second yarn with anagent that renders the second yarn resistant to uptake of the selecteddye.
 6. A method according to claim 1, wherein the first yarn is of adifferent type from the second yarn, such that the first yarn has agreater affinity for the selected dye than has the second yarn.
 7. Amethod according to claim 6, first and second yarns are of differentchemical composition.
 8. A method according to claim 7, wherein thefirst yarn is a cellulosic yarn and the second yarn is a polyester yarn.9. A method according to claim 1, wherein step (a) includes providing athird yarn having a smaller affinity for the selected dye than thesecond yarn and step (b) comprises creating a fabric using the first,second and third yarns.
 10. A method according to claim 9, wherein thethird yarn is a blend of cellulosic and non-cellulosic fibers.
 11. Amethod according to claim 9, wherein the third yarn is a blend of cottonand polyester fibers.
 12. A method according to claim 9, wherein thethird yarn is a solid base synthetic fiber yarn.
 13. A method ofprinting a fabric article formed from cellulosic fibers, comprising: a)printing the article with a dye gain print paste including an acryliccopolymer, and b) thereafter dyeing the article.
 14. A method accordingto claim 13, wherein the dye gain print paste contains styrene monomersand acrylates.
 15. A method according to claim 13, further comprising,between steps (a) and (b): cutting the fabric article into garmentpieces, and making up the garment pieces into garment modules, andwherein step (b) is a garment dyeing step.
 16. A method of printing afabric article formed from cellulosic fibers, comprising: a) printingthe article with a dye resist print paste including an acryliccopolymer, and b) thereafter dyeing the article.
 17. A method accordingto claim 16, further comprising, between steps (a) and (b): cutting thefabric article into garment pieces, and making up the garment piecesinto garment modules, and wherein step (b) is a garment dyeing step.